Many injuries to joints result in long term disuse in order for the joint structures to heal. A result of this is that there is joint stiffness and possible muscular atrophy which must be restored for the patient to reacquire extremity usage. For example, considering rotator cuff injuries of baseball or football players or elderly patients with various bone fractures or arthritis, these type of patients need to have power-assisted exercise of the joints and associated musculature in order to rebuild the muscles for functional use.
A number of machines currently exist to provide for the appropriate joint exercise. For example, Pechuex U.S. Pat. No. 4,577,623 illustrates a continuous passive motion (hereinafter "CPM") device for upper extremities which exercises the shoulder and arm. This machine provides for forward flexion/extension, abduction/adduction with or without external/internal rotation of the shoulder by means of various motor-driven levers, pulley and cable systems.
The Pecheux machine is currently commercially available as the kinetic brand shoulder CPM machine made by COGEMO S.A. of Tournes, France, and distributed by Richards Medical Company of Memphis, Tenn. The machine is mounted on a vertical shaft fastened to a four-legged horizontal base having castors. Two of the legs are short and extend outboard of the machine, and the two other legs are substantially longer in order to extend underneath a chair provided by a patient. The long pair of legs also prevents the device from tipping over, it being necessary to spread the weight since the CPM unit has several active arms and other elements which are cantilevered out from the center line of the vertical support post. Accordingly, the entire unit needs to be counter-balanced by the long legs. COGEMO also offers, through Richards Medical Company, an elbow CPM for passive flexion/extension of the elbow without associated pronation/supination of the wrist.
These CPM devices are current state of the art for both passive and active resistive therapy for a variety of surgical and chronic etiologies. But they pose problems in proper utilization for specific therapy requirements, because proper patient positioning with respect to the machine is important, if not critical. In many instances, the patient uses this machine by him/herself at home after limited instruction. The chair is usually provided by the patient. Because both the height, size and nature of the chair used by the patient and the size and mobility of the patient ranges widely, patient positioning problems become significant. Further, after the physical therapist leaves the patient, the patient may shift the chair with respect to the machine, and what becomes prescribed passive abduction/adduction of the shoulder with or without associated external/internal rotation could drift into an external or internal rotation motion that is not prescribed. Further, the patient may move too far away from the machine, thus encouraging spinal curvature and discomfort. Usually the chair does not have appropriate lumbar support, thus aggravating an independent or associated spinal condition during rehabilitation.
In addition, because of the length and spread of the base leg assembly of the CPM unit, and the leg height off the floor, the unit can not accept many kinds of chairs, or the position of the patient with respect to the chair is constrained and awkward. That is, the patient must sit on the chair in an unnatural position because the chair will not fit properly with respect to the machine. This leads to improper or incomplete exercise, or leads to early fatigue of the patient. Further, the patient becomes discouraged from use of the rehabilitation unit, and rehabilitation is delayed or becomes counter-productive. These are just a few of the problems which arise because of the construction of the current state of the art CPM machines.
Accordingly, there is a need in the art for an accurate positioning system which properly positions the patient in the correct posture and the correct distance from the machine, yet which is adjustable along all axes to provide for a full range of active and passive resistive therapy for a wide variety of surgical, chronic and age-related etiologies, yet is both totally adaptable to specific therapy requirements and allows for progressive changes in therapy, and which once positioned by the rehabilitation specialist is not subject to inadvertent patient change leading to improper positioning and use.